A concentric two-component cartridge and a corresponding dispenser with concentric plungers arranged to engage corresponding concentric pistons on the cartridge is disclosed in U.S. Pat. No. 4,366,919. U.S. Pat. No. 6,454,138 discloses a similar dispenser for concentric two-component cartridges, which is reconfigurable to fit different cartridges. By removing or reconfiguring an inner one of two concentric plunger portions, component cartridges of different component ratios, or in other words different inner compartment diameters, can be used with the same dispenser. By removing an outer one of the concentric plunger portions, the dispenser can be used with single component cartridges.
WO-A-2005/095225 discloses a plunger having two plunger portions arranged to engage a respective piston of either a 10:1 or 1:1 two-component cartridge (or of a corresponding single component cartridge) without the need for reconfiguring the plunger. The plunger has an inner plunger portion which has a face smaller than a corresponding inner piston of the 1:1 cartridge and an outer plunger portion which has an annular face smaller than a corresponding outer piston of the 10:1 cartridge. Both plunger portions engage the piston of the single component cartridge. Thus, the same plunger can be used with three different cartridges, all of the same outer diameter. It would be desirable for the plunger to be useable with a larger number of piston configurations and also with cartridges having different outer diameters.